An efficient Progressive Swapping to the Middle distribution protocol adapted to imperfect quantum memories in quantum networks

2026-05-29

AI Summary

This work addresses the low efficiency and high resource overhead of end-to-end entanglement generation in quantum networks equipped with imperfect quantum memories. To overcome these challenges, the authors propose the Progressive Swap-to-Middle (PSM) protocol, which introduces a novel bidirectional progressive entanglement swapping mechanism. In PSM, entanglement swapping operations are initiated synchronously from both ends of a path and converge at a central node to complete the connection—a strategy that uniquely integrates bidirectional operation with a middle-convergence approach for the first time. Under realistic constraints imposed by memory decoherence, PSM significantly enhances link establishment success probability while maintaining acceptable fidelity with superior resource efficiency compared to existing parallel protocols.

Abstract

The distribution of entangled pairs of photons on the links composing a quantum network, combined with Bell state measurements and teleportation, is the basic apparatus to transfer quantum bits (qubits) over long distances. Entanglement distribution establishes an end-to-end entangled pair while consuming intermediate pairs on links and holding them for a certain time period. The technical literature identifies two main kinds of protocols, parallel and sequential ones, the latter having an advantage in resource consumption over the former. In this paper, we introduce an efficient swapping protocol called Progressive Swapping to the Middle (PSM) as it combines the existing Progressive Swapping (PS) protocol from both extremities of a path that meet in the middle where the received pairs are swapped. We compare PSM with two parallel protocols and PS; in our evaluation, we take into account imperfect memories and fidelity degradation. We demonstrate that PSM yields a much better link probability than PS while keeping a reasonable link fidelity, and shows an advantage in resource consumption over other protocols.

Problem

• quantum networks
• entanglement distribution
• imperfect quantum memories
• swapping protocol
• resource consumption

Innovation

• Progressive Swapping to the Middle
• quantum networks
• entanglement distribution
• imperfect quantum memories
• resource-efficient protocol